Coseismic Deformation Obtained by Various Technical Methods and Its Constraint Ability to Slip Models of Maduo Earthquake

Abstract

The coseismic deformation field on both sides of the fault, especially the distribution and change characteristics of near-field deformation, not only provides important constraints for the fine inversion of the slip distribution model but also serves as an important basis for the anti-disruption defense of the cross-fault linear engineering facilities. In this paper, we used Sentinel-1 satellite data to obtain the coseismic deformation field of the Maduo earthquake by using InSAR and offset techniques. We quantitatively compared the coseismic displacement of the three types of data: InSAR, offset, and optical images. The results show that optical images and offset provided more robust near-fault (<2 km) deformation insights than InSAR, which exhibited irregular deformation patterns due to incoherence near the fault. The maximum relative displacements for InSAR and offset observations are ~2.8 m and 4 m, respectively. Then we tested various fault slip models with different data constraints, revealing that a combined inversion of GPS, InSAR, and offset data offers superior constraints on slip distribution. This integrative approach effectively captured both shallow and deep fault slip, particularly near the fault zone. The eastern branch fault model, jointly constrained by GPS, InSAR, and offset data, is the optimal coseismic slip distribution model for the Maduo earthquake, and the maximum slip is 5.55 m.